1. Field of the Invention
The present invention relates to a drawing apparatus, a method of manufacturing an article, and a processing apparatus.
2. Description of the Related Art
In recent years, since the characteristics of electronic devices placed in a vacuum apparatus change depending on the temperature, heat generation sources are often located in the exterior of a vacuum chamber, which can be easily cooled. A vacuum apparatus shown in FIG. 12 uses a photodiode 301 located in a vacuum chamber interior 401 to detect a laser beam 222, and uses an amplifier 306 to generate a pulse waveform in proportion to the amount of received light. With an increase in detection frequency, the amplifier 306 generates a larger amount of heat, and the generated heat degrades the detection characteristics of the photodiode 301. Therefore, the amplifier 306 is located in a vacuum chamber exterior 402 via a vacuum feedthrough 304. As the amplifier 306 is located in the vacuum chamber exterior 402, it can be sufficiently cooled by a cooler 209. Also, as the amplifier 306 is spaced apart from the photodiode 301, heat is prevented from being transferred to the photodiode 301. However, with an increase in transmission distance between the photodiode 301 and the amplifier 306, the transmission characteristics degrade. Also, in such a vacuum apparatus which requires a large number of electronic devices, the number of placeable electronic devices is limited due to a constraint in size of components to be mounted, including the vacuum feedthrough 304.
Similarly, a drawing apparatus which draws using a plurality of charged particle beams is often employed as a vacuum apparatus which includes electronic devices that may produce an adverse effect resulting from heat generation, and poses a problem due to factors associated with transmission lines through which signals are transmitted to these electronic devices. FIGS. 14 and 15 illustrate examples of blanking electrodes 208 of a blanking deflector in a conventional drawing apparatus disclosed in Japanese Patent Laid-Open No. 9-7538, drivers which drive the blanking electrodes 208, and transmission lines through which driving signals are transmitted to the blanking electrodes 208. A control circuit 5 of a blanking deflector 16 outputs driving signals to drivers 501. These outputs are connected to interface connectors 202 of a relay substrate (junction substrate) 520 via signal cables 201, and pass through an electron optical system barrel (electron optical system housing; vacuum chamber) 206 in accordance with the wiring pattern. The driving signals having passed through terminators 504 serving as their termination circuits pass through a vacuum seal 510 and are connected to the blanking deflector 16 via contact units 505. A pair of blanking electrodes 208 placed in each blanking aperture 507 is located on the blanking deflector 16, and the driving signals are connected from the contact units 505 to the blanking electrodes 208 via a wiring pattern 506. Also, a coolant is supplied from the cooler 209 to an inlet pipe 514, the relay substrate 520, and an outlet pipe 513 to remove heat generated by the terminator 504, thereby controlling thermal deformation and changes in characteristics of members present inside the electron optical system barrel 206 and the vacuum seal 510.
It is desired to further improve the throughput of such a drawing apparatus. To improve the throughput of the drawing apparatus, it is effective to shorten the interval between repetitions of drawing, that is, the drawing cycle. However, to do this, it is necessary to shorten the blanking time, so the frequency of a control signal for the blanking deflector 16 increases. Again, to improve the throughput of the drawing apparatus, it is also effective to widen the drawing range of one charged particle beam source, that is, the angle of view, so the number of charged particle beams split by an aperture array can be increased. To do this, it is necessary to increase the numbers of electrostatic lenses and blanking deflectors 16 which control the split charged particle beams. This, in turn, makes it necessary to increase the numbers of lenses, electrodes, and eventually wiring lines running to the electrodes.
To shorten the drawing cycle, it is necessary to transmit control signals at high speed. However, maintaining or improving the transmission characteristics to shorten the drawing cycle, and increasing the number of wiring lines to widen the angle of view have a tradeoff relationship. Further, conventionally, signals are transmitted via the wiring pattern of the relay substrate from the exterior of the electron optical system barrel 206 to the electrodes located at nearly the center in the electron optical system barrel 206, and the wiring length has a value (several hundred millimeters) close to the radius of the electron optical system barrel 206. At present, the required frequency components of the driving signals for the blanking electrodes come close to 1 GHz with an apparatus speedup. In such a signal frequency range, the constraints in transmission line capacitance and DC resistance are large. When the transmission line is designed to have a width of, for example, 2 μm, the capacitance of the line other than the capacitances of the blanking electrodes is 1.5 PF, and the DC resistance is 300Ω, the allowable line length calculated from various other conditions is only 15 mm.
To improve the throughput of a drawing apparatus which draws using a plurality of charged particle beams, it is necessary to transmit a large volume of signals at high speed (high frequencies). To do this, it is necessary to widen the wiring region to increase the size of the wiring pattern or shorten the wiring length. First, as a method of widening the wiring region, multilayer wiring is practicable. In this case, a plurality of transmission lines connected from a control signal generation portion using cables via a multilayer wiring device, a multilayer wiring substrate, and a relay substrate are formed by a plurality of electrodes. This method can produce a certain effect, but the number of layers has a limit in terms of manufacture. It is difficult to form high-density wiring and mounting using a currently practicable number of layers (about 50 layers) while maintaining desired transmission characteristics.
On the other hand, to shorten the wiring length on a substrate, a method of shortening the wiring length on a substrate by connecting a cable having an impedance lower than wiring into an electron optical system barrel in a vacuum feedthrough configuration, and locating a photoelectric conversion element or a serial-parallel converter near a blanking electrode array is available. However, because the photoelectric conversion element or serial-parallel converter generates heat near the blanking electrode array, geometric strain may occur in the structure of the blanking electrode array to a degree that cannot be ignored in terms of drawing accuracy. Also, a problem is posed due to factors associated with the mounting volume of the cable in the electron optical system barrel, and a measure against outgassing from the cable and photoelectric conversion element is necessary, leading to increases in apparatus size and cost. The above-mentioned method can shorten the wiring length to improve the transmission characteristics, but poses another problem.